Concentration profiles of cis-platin in the cortex and cerebellum of the rat were analyzed with the intent of determining transport and reaction rate parameters. These parameters are needed to prospectively model various tumor treatment modalities for expected efficacy. A reaction-diffusion model was formulated for cis-platin infusion from point and near-point sources. Both infinite and finite spherical transport regions were modeled, the latter to demonstrate that drug flow into the cerebral spinal fluid is of secondary importance. It was shown that the experimental concentration profiles corresponded to steady state conditions, and could be modeled by simpler steady-state mathematics. Convection due to diluent flow from the infusion cannula was added to the reaction-diffusion model. Steady-state analysis showed that convection substantially modified the concentration profiles only over the first millimeter from the cannula tip. More realistc geometry was introduced modelling the cerebellum as a prolate ellipsoid. Average total Pt concentrations for sections across this ellipsoid were fit to corresponding experimental tissue section data. The resulting fit, constrained by an independent measure of infusate recovery, provided estimates for cis-plating capillary permeability (9.03x10 to the-7 cm/sec) and reaction rate (.005/min). The tissue diffusion constant was estimated as 1.9x10 to the-6/sec, similar to creatinine due to the small hydrodynamic radius of cis-platin. The permeability is within the range predicted from octanol-saline partition coefficient/permeabillty correlations. The reaction rate compares with values reported for other tissues.